1. Field of the Invention
The invention relates to strain gages and more particularly to strain gages adapted to be employed in an environment wherein elevated temperatures operatively are encountered.
2. Description of the Prior Art
The prior art is replete with strain gages for measuring strain resulting from mechanical stress. Attempts have been made to employ various types of known strain gages in measuring mechanical strain imparted to specimens while the specimens are maintained at elevated temperatures, and accordingly are subjected to thermal expansion strain. However, such attempts have not always met with success as various impediments normally are encountered. For example, where optical techniques are employed in measuring mechanically imparted strain, in samples subjected to thermal inputs, an attendant inability to effectively cancel thermal expansion strain persists. Where the techniques being employed require the use of devices based on a change in capacitance, an attendant change in dielectric constant and an inability to adequatedly cancel the effects of the source of thermal energy have impeded the use of such devices. Where devices, such as the device disclosed in U.S. Pat. No. 3,293,909, are employed, such devices fail to totally satisfy existing needs since these devices do not readily accommodate real-time observation of performance.